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.TH PTHREAD_RWLOCK_TIMEDWRLOCK 3C "Jan 30, 2004"
.SH NAME
pthread_rwlock_timedwrlock, pthread_rwlock_reltimedwrlock_np \- lock a
read-write lock for writing
.SH SYNOPSIS
.LP
.nf
cc \fB-mt\fR [ \fIflag\fR... ] \fIfile\fR... [ \fIlibrary\fR... ]
#include <pthread.h>
#include <time.h>

\fBint\fR \fBpthread_rwlock_timedwrlock\fR(\fBpthread_rwlock_t *restrict\fR \fIrwlock\fR,
     \fBconst struct timespec *restrict\fR \fIabs_timeout\fR);
.fi

.LP
.nf
\fBint\fR \fBpthread_rwlock_reltimedwrlock_np\fR(\fBpthread_rwlock_t *restrict\fR \fIrwlock\fR,
     \fBconst struct timespec *restrict\fR \fIrel_timeout\fR);
.fi

.SH DESCRIPTION
.LP
The \fBpthread_rwlock_timedwrlock()\fR function applies a write lock to the
read-write lock referenced by \fIrwlock\fR as in the
\fBpthread_rwlock_wrlock\fR(3C) function. If the lock cannot be acquired
without waiting for other threads to unlock the lock, this wait will be
terminated when the specified timeout expires. The timeout expires when the
absolute time specified by \fIabs_timeout\fR passes, as measured by the
\fBCLOCK_REALTIME\fR clock (that is, when the value of that clock equals or
exceeds \fIabs_timeout\fR), or if the absolute time specified by
\fIabs_timeout\fR has already been passed at the time of the call.
.sp
.LP
The \fBpthread_rwlock_reltimedwrlock_np()\fR function is identical to the
\fBpthread_rwlock_timedwrlock()\fR function, except that the timeout is
specified as a relative time interval. The timeout expires when the time
interval specified by \fIrel_timeout\fR passes, as measured by the
\fBCLOCK_REALTIME\fR clock, or if the time interval specified by
\fIrel_timeout\fR is negative at the time of the call.
.sp
.LP
The resolution of the timeout is the resolution of the \fBCLOCK_REALTIME\fR
clock. The \fBtimespec\fR data type is defined in the <\fBtime.h\fR> header.
Under no circumstances does either function fail with a timeout if the lock can
be acquired immediately. The validity of the \fIabs_timeout\fR parameter need
not be checked if the lock can be immediately acquired.
.sp
.LP
If a signal that causes a signal handler to be executed is delivered to a
thread blocked on a read- write lock with a call to
\fBpthread_rwlock_timedwrlock()\fR or \fBpthread_rwlock_reltimedwrlock_np()\fR,
upon return from the signal handler the thread resumes waiting for the lock as
if it was not interrupted.
.sp
.LP
The calling thread can deadlock if at the time the call is made it holds the
read-write lock. The results are undefined if this function is called with an
uninitialized read-write lock.
.SH RETURN VALUES
.LP
The \fBpthread_rwlock_timedwrlock()\fR and
\fBpthread_rwlock_reltimedwrlock_np()\fR functions return 0 if the lock for
writing on the read-write lock object referenced by \fIrwlock\fR is acquired.
Otherwise, an error number is returned to indicate the error.
.SH ERRORS
.LP
The \fBpthread_rwlock_timedwrlock()\fR and
\fBpthread_rwlock_reltimedwrlock_np()\fR functions will fail if:
.sp
.ne 2
.na
\fB\fBETIMEDOUT\fR\fR
.ad
.RS 13n
The lock could not be acquired before the specified timeout expired.
.RE

.sp
.LP
The \fBpthread_rwlock_timedwrlock()\fR and
\fBpthread_rwlock_reltimedwrlock_np()\fR functions may fail if:
.sp
.ne 2
.na
\fB\fBEDEADLK\fR\fR
.ad
.RS 11n
The calling thread already holds the rwlock.
.RE

.sp
.ne 2
.na
\fB\fBEINVAL\fR\fR
.ad
.RS 11n
The value specified by \fIrwlock\fR does not refer to an initialized read-write
lock object, or the timeout nanosecond value is less than zero or greater than
or equal to 1,000 million.
.RE

.SH ATTRIBUTES
.LP
See \fBattributes\fR(7) for descriptions of the following attributes:
.sp

.sp
.TS
box;
c | c
l | l .
ATTRIBUTE TYPE	ATTRIBUTE VALUE
_
Interface Stability	See below.
_
MT-Level	MT-Safe
.TE

.sp
.LP
The \fBpthread_rwlock_timedwrlock()\fR function is Standard. The
\fBpthread_rwlock_reltimedwrlock_np()\fR function is Stable.
.SH SEE ALSO
.LP
.BR pthread_rwlock_destroy (3C),
.BR pthread_rwlock_rdlock (3C),
.BR pthread_rwlock_timedrdlock (3C),
.BR pthread_rwlock_trywrlock (3C),
.BR pthread_rwlock_unlock (3C),
.BR pthread_rwlock_wrlock (3C),
.BR attributes (7),
.BR standards (7)
